/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2012-2016 Symless Ltd.
 * Copyright (C) 2004 Chris Schoeneman
 * 
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file LICENSE that should have accompanied this file.
 * 
 * This package is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "platform/XWindowsEventQueueBuffer.h"

#include "mt/Lock.h"
#include "mt/Thread.h"
#include "base/Event.h"
#include "base/IEventQueue.h"

#include <fcntl.h>
#if HAVE_UNISTD_H
#	include <unistd.h>
#endif
#if HAVE_POLL
#	include <poll.h>
#else
#	if HAVE_SYS_SELECT_H
#		include <sys/select.h>
#	endif
#	if HAVE_SYS_TIME_H
#		include <sys/time.h>
#	endif
#	if HAVE_SYS_TYPES_H
#		include <sys/types.h>
#	endif
#endif

//
// EventQueueTimer
//

class EventQueueTimer { };


//
// XWindowsEventQueueBuffer
//

XWindowsEventQueueBuffer::XWindowsEventQueueBuffer(
		Display* display, Window window, IEventQueue* events) :
	m_events(events),
	m_display(display),
	m_window(window),
	m_waiting(false)
{
	assert(m_display != NULL);
	assert(m_window  != None);

	m_userEvent = XInternAtom(m_display, "SYNERGY_USER_EVENT", False);
	// set up for pipe hack
	int result = pipe(m_pipefd);
	assert(result == 0);

	int pipeflags;
	pipeflags = fcntl(m_pipefd[0], F_GETFL);
	fcntl(m_pipefd[0], F_SETFL, pipeflags | O_NONBLOCK);
	pipeflags = fcntl(m_pipefd[1], F_GETFL);
	fcntl(m_pipefd[1], F_SETFL, pipeflags | O_NONBLOCK);
}

XWindowsEventQueueBuffer::~XWindowsEventQueueBuffer()
{
	// release pipe hack resources
	close(m_pipefd[0]);
	close(m_pipefd[1]);
}

void
XWindowsEventQueueBuffer::waitForEvent(double dtimeout)
{
	Thread::testCancel();

	// clear out the pipe in preparation for waiting.

	char buf[16];
	ssize_t read_response = read(m_pipefd[0], buf, 15);
	
	// with linux automake, warnings are treated as errors by default
	if (read_response < 0)
	{
		// todo: handle read response
	}

	{
		Lock lock(&m_mutex);
		// we're now waiting for events
		m_waiting = true;

		// push out pending events
		flush();
	}
	// calling flush may have queued up a new event.
	if (!XWindowsEventQueueBuffer::isEmpty()) {
		Thread::testCancel();
		return;
	}

	// use poll() to wait for a message from the X server or for timeout.
	// this is a good deal more efficient than polling and sleeping.
#if HAVE_POLL
	struct pollfd pfds[2];
	pfds[0].fd     = ConnectionNumber(m_display);
	pfds[0].events = POLLIN;
	pfds[1].fd     = m_pipefd[0];
	pfds[1].events = POLLIN;
	int timeout    = (dtimeout < 0.0) ? -1 :
						static_cast<int>(1000.0 * dtimeout);
	int remaining  =  timeout;
	int retval     =  0;
#else
	struct timeval timeout;
	struct timeval* timeoutPtr;
	if (dtimeout < 0.0) {
		timeoutPtr = NULL;
	}
	else {
		timeout.tv_sec  = static_cast<int>(dtimeout);
		timeout.tv_usec = static_cast<int>(1.0e+6 *
								(dtimeout - timeout.tv_sec));
		timeoutPtr      = &timeout;
	}

	// initialize file descriptor sets
	fd_set rfds;
	FD_ZERO(&rfds);
	FD_SET(ConnectionNumber(m_display), &rfds);
	FD_SET(m_pipefd[0], &rfds);
 	int nfds;
 	if (ConnectionNumber(m_display) > m_pipefd[0]) {
 		nfds = ConnectionNumber(m_display) + 1;
 	}
 	else {
 		nfds = m_pipefd[0] + 1;
 	}
#endif
	// It's possible that the X server has queued events locally
	// in xlib's event buffer and not pushed on to the fd. Hence we
	// can't simply monitor the fd as we may never be woken up.
	// ie addEvent calls flush, XFlush may not send via the fd hence
	// there is an event waiting to be sent but we must exit the poll
	// before it can.
	// Instead we poll for a brief period of time (so if events
	// queued locally in the xlib buffer can be processed)
	// and continue doing this until timeout is reached.
	// The human eye can notice 60hz (ansi) which is 16ms, however
	// we want to give the cpu a chance s owe up this to 25ms
#define TIMEOUT_DELAY 25

	while (((dtimeout < 0.0) || (remaining > 0)) && QLength(m_display)==0 && retval==0){
#if HAVE_POLL
	retval = poll(pfds, 2, TIMEOUT_DELAY); //16ms = 60hz, but we make it > to play nicely with the cpu
 	if (pfds[1].revents & POLLIN) {
 		ssize_t read_response = read(m_pipefd[0], buf, 15);
		
		// with linux automake, warnings are treated as errors by default
		if (read_response < 0)
		{
			// todo: handle read response
		}

 	}
#else
	retval = select(nfds,
						SELECT_TYPE_ARG234 &rfds,
						SELECT_TYPE_ARG234 NULL,
						SELECT_TYPE_ARG234 NULL,
						SELECT_TYPE_ARG5   TIMEOUT_DELAY);
	if (FD_SET(m_pipefd[0], &rfds)) {
		read(m_pipefd[0], buf, 15);
	}
#endif
	    remaining-=TIMEOUT_DELAY;
	}

	{
		// we're no longer waiting for events
		Lock lock(&m_mutex);
		m_waiting = false;
	}

	Thread::testCancel();
}

IEventQueueBuffer::Type
XWindowsEventQueueBuffer::getEvent(Event& event, UInt32& dataID)
{
	Lock lock(&m_mutex);

	// push out pending events
	flush();

	// get next event
	XNextEvent(m_display, &m_event);

	// process event
	if (m_event.xany.type == ClientMessage &&
		m_event.xclient.message_type == m_userEvent) {
		dataID = static_cast<UInt32>(m_event.xclient.data.l[0]);
		return kUser;
	}
	else {
		event = Event(Event::kSystem,
							m_events->getSystemTarget(), &m_event);
		return kSystem;
	}
}

bool
XWindowsEventQueueBuffer::addEvent(UInt32 dataID)
{
	// prepare a message
	XEvent xevent;
	xevent.xclient.type         = ClientMessage;
	xevent.xclient.window       = m_window;
	xevent.xclient.message_type = m_userEvent;
	xevent.xclient.format       = 32;
	xevent.xclient.data.l[0]    = static_cast<long>(dataID);

	// save the message
	Lock lock(&m_mutex);
	m_postedEvents.push_back(xevent);

	// if we're currently waiting for an event then send saved events to
	// the X server now.  if we're not waiting then some other thread
	// might be using the display connection so we can't safely use it
	// too.
	if (m_waiting) {
		flush();
		// Send a character through the round-trip pipe to wake a thread
		// that is waiting for a ConnectionNumber() socket to be readable.
		// The flush call can read incoming data from the socket and put
		// it in Xlib's input buffer.  That sneaks it past the other thread.
		ssize_t write_response = write(m_pipefd[1], "!", 1);

		// with linux automake, warnings are treated as errors by default
		if (write_response < 0)
		{
			// todo: handle read response
		}
	}

	return true;
}

bool
XWindowsEventQueueBuffer::isEmpty() const
{
	Lock lock(&m_mutex);
	return (XPending(m_display) == 0 );
}

EventQueueTimer*
XWindowsEventQueueBuffer::newTimer(double, bool) const
{
	return new EventQueueTimer;
}

void
XWindowsEventQueueBuffer::deleteTimer(EventQueueTimer* timer) const
{
	delete timer;
}

void
XWindowsEventQueueBuffer::flush()
{
	// note -- m_mutex must be locked on entry

	// flush the posted event list to the X server
	for (size_t i = 0; i < m_postedEvents.size(); ++i) {
		XSendEvent(m_display, m_window, False, 0, &m_postedEvents[i]);
	}
	XFlush(m_display);
	m_postedEvents.clear();
}
